I've been using all of my macs for years now without Apple IDs. I use them only reluctantly on iOS devices to install apps, and don't use iCloud (it's a privacy nightmare).
Relying on Apple to remain benevolent when the incentives are so misaligned is a fool's errand.
What do you use instead?
I use syncthing to synchronize my computers and I use Ente to store and sync my photos.
My computer files aren’t on my phone or vice versa.
I use IMAP email so it’s accessible on both.
I use Signal instead of iMessage.